Vertebrate Physiology Exam 1 Study Guide
Vertebrate Physiology Exam 1 Study Guide BIOL 3270
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This 8 page Study Guide was uploaded by Maci Winn on Sunday January 31, 2016. The Study Guide belongs to BIOL 3270 at Southern Utah University taught by Dr. Weeg in Winter 2016. Since its upload, it has received 63 views. For similar materials see Vertebrate Physiology in Biology at Southern Utah University.
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Date Created: 01/31/16
Vertebrate Physiology: Unit 1 Exam Study Guide Physiology: the study of how an organism functions Levels of Organization: ChemicalCellularTissuesOrgansBody system Emergent properties: new properties that arise from synergism that aren’t predicted Controlled VariableSensorsIntegrating Center (CNS)Effectors (glands/muscles)Response Reset Control: Change range for variable Homeostasis: maintaining similar conditions within the body Negative feedback: a change that initiates a sequence of events that removes a response Example: increased concentration of a hormone in a pathway can inhibit the production of that hormone until the concentration has decreased Positive feedback: a mechanism that accentuates an initial change Example: oxytocin is secreted during childbirth to produce stronger muscle contractions to push the baby Membrane Transport INTRO QUESTION: Why would glucose be absorbed faster into the bloodstream from chocolate with sea salt than plain chocolate? The sodium gradient increases because of the intake of sodium from the salted chocolate, and this increases the rate that the SGLT transporter transports glucose and sodium into the cell. This would also increase the rate of the sodium-potassium pump to keep the intracellular concentration of sodium the same. Passive transport: transport that does not require energy and Simple diffusion: diffusion through phospholipids Molecules move along concentration gradient in and out of the cell Small, non-polar molecules Facilitated diffusion: diffusion through proteins 1. Channel proteins • Made of trans-membrane protein subunits • These include: • Aquaporins (water transport through the membrane) • Ion channels • Fast, bidirectional (molecules are transported in two directions) • May or may not be selective • There can be open and gated channels 2. Carrier proteins • Made of trans-membrane protein subunits • Open only to one side of membrane at a time • Changes conformation upon the binding of ligands to transport molecule • Slow, unidirectional (transports molecules one way only) • Only specific molecules will bind to carrier protein to be transported • Uniport carriers (one single molecule at a time) • Co-transporters • Symport (two molecules at once in the same direction) • Antiport (two molecules in opposite directions) Active transport: energy dependent transport (i.e. ATP) that moves molecules against the concentration gradient. There is primary and secondary transport. This can be conducted through carrier proteins. Primary active transport • Uses ATP direc+ly+ • Example: Na /K pump • The sodium potassium pump binds 3 Na+ ions and removes from the cell, and then undergoes a conformational change to bind 2 K+ ions and brings them into the cell. This prevents the inside concentration of Na+ getting too high and from the K+ concentration getting too low. • Uses to 30% of cell’s ATP!!! Secondary active transport • Uses ATP indirectly • ATP creates concentration gradient of 1 solutet • Concentration gradient powers active transport of 2 ndsolute • Example: SGLT transporter • The SGLT transporter is a symport that uses the gradient power of Na+ from the Na/K pump, and moves one glucose molecule and one Na+ ion into the cell, making the intracellular concentration of glucose higher than the extracellular concentration. Cells use many different transporters Example: transporting epithelium • Apical membrane • SGLT transporter • Basolateral membrane • GLUT transporter • Na /K pump Vesicular transport There are 3 different types: Phagocytosis, endocytosis (includes both pinocytosis and receptor-mediated endocytosis), and exocytosis. Cellular Communication INTRO QUESTION: How do cells become permeable to glucose? • GLUT transporters are receptor enzymes. They change conformation upon the binding of insulin that allows the transport of glucose. Phosphorylation of the transporter via a tyrosine kinase inserts the vesicle into the membrane for transport, and when insulin is no longer around to activate it, it will remove itself from the membrane. Intercellular communication: There is direct and indirect communication in a cell • Direct communication includes gap junctions, transient direct linkup, and nanotubules • Indirect communication includes paracrines/autocrines, hormones, cytokines, neurotransmitters, and neurohormones. • Paracrines are released into the interstitial fluid (ISF) and move short distances because they are transported via diffusion • Cytokines can be released into the blood (long distance transport) and into the ISF • Neurotransmitters and neurohormones are released into the ISF via neurons and act on adjacent cells Signal Pathways 2 categories of signal molecule • Lipophilic (“likes” lipids—nonpolar and diffuses through membrane) • Bind to cytosolic or nuclear receptors • Alter gene activity – slow • Lipophobic (“dislikes” lipids—polar, enter through membrane bound receptors.) • Bind to membrane receptors • Alter protein activity – fast Signal transduction • Converts extracellular signal into intracellular response • 2ndmessenger systems • Second messenger systems activate protein kinases and phosphatases (phosphorylation and dephosphorylation enzymes), increase intracellular calcium, and alter channel gating. • Signal cascades (activation of one hormone via cell signal activates another hormone) • Signal amplification (active hormones activate multiple other hormones) Cell Receptors 1. Receptor-channels, which can be chemical or ligand gated channels. Specific pathways are activated by calcium. 2. Receptor enzymes, include kinases and phosphatases where extracellular binding on an integral protein occurs and activates internal enzyme activity. 3. G protein-coupled receptors, which includes ligand binding extracellularly changing the conformation of the receptor and activates the G-protein that signals a cascade of responses. Receptor-channels • Chemically- (ligand-) gated channels • Opened/closed by: • Extracellular ligand binding • G protein activity • Intracellular signal molecules • Effects of altered permeability • Changes in electrical activity • Changes in intracellular Calcium concentration Receptor-enzymes • Protein kinases • Protein phosphorylation G protein-coupled receptors • Ligand binding activates G protein • G protein can: • Activate protein kinases 2+ • Increase intracellular Ca • Open/close ion channels What determines the cell’s response? Major factors • Ligand • Agonist vs. antagonist • Receptor • “Same key, different locks” • Isoforms • Up/down-regulation • 2nd messenger pathway Hormones INTRO QUESTION: Why does steroid use decrease sperm production? • Steroids significantly increase testosterone, which decreases the hormones in step 1 and 2 of the pathway via negative feedback. FSH and testosterone are both required for sperm production so production will be significantly decreased. Hormones are secreted into the blood by cells or glands and can be active at very long concentrations, and can act on long distance targets. • Affect metabolic processes Hormone Classes 1) Peptide/protein hormones 2) Steroid hormones (Derived from cholesterol) 3) Amine hormones (Catecholamines and thyroid hormones) Hormone Concentrations • Depend on secretion rate and mechanism of transport. Only free hormone is active and changes in transport proteins alter hormone concentration Secretion Main control mechanisms • Negative-feedback • Maintains stable plasma concentration • Neuroendocrine reflexes • Rapidly increases plasma concentration in response to stimulus • Rhythmic release • Plasma concentration fluctuates over time Interactions Categories • Synergism • Permissiveness • Antagonism The pituitary gland Posterior pituitary • Releases 2 neurohormones • Vasopressin (vasotocin) • Oxytocin (mesotocin) • Sequence of events: • Made in hypothalamic neurons • Released in posterior pituitary • Distributed to body via blood Anterior pituitary • Hypothalamic-hypophyseal portal system • Hypothalamic neurohormones (hypophysiotropic hormones) released into portal system • Anterior pituitary hormones released into circulation • Targets release their hormones Anterior pituitary: The six hormones it secretes (MEMORIZE) 1) Prolactin 2) Growth hormone (GH) 3) Follicle stimulating hormone (FSH) 4) Luteinizing hormone (LH) 5) Thyroid-stimulating hormone (TSH) 6) Adrenocorticotropic hormone (ACTH) Pituitary feedback loops • Hormones (not response) are involved in negative feedback INTRO QUESTION: What effect does the Na/K pump have on membrane potential? • The Na+/K+ pump brings 3 Na+ out of the cell while bringing 2K+ into the cell, making the cell more negative causing the cell to hyperpolarize. Membrane Potential Bioelectricity Cells at rest… • Ion concentrations • Na & K concentrations established & maintained by Na /K + + pump • High Na+ concentration and low K+ concentration outside cell • Low Na+ and high K+ concentration inside cell • Na /K pump brings 3 Na+ out of the cell while moving 2 K+ inside the cell • Ion permeabilities • High permeability to K + • Low permeability to Na + • More K+ leak channels than N+ leak channels Membrane potential (Vm) • Separation of electrical charge across the cell membrane • Represents energy (or potential) to do work Membrane potential • Measured in millivolts (mV) • Magnitude depends on # of separated charges Resting membrane potential • Stable potential of a cell at rest • ~ -70mV • Influenced by ion concentration gradients & permeabilities • If the membrane is completely impermeable to the ion then the Vm=0 • A K+ leak would cause K+ to flow out of the cell making Vm<0 • A Na+ leak would cause Na+ to flow into the cell making Vm>0 • This develops a concentration gradient as well as an electrical gradient • Equilibrium potential (E (ion)is the membrane potential at which the electrical gradient is equal but opposite to the concentration gradient. Every ion has its own equilibrium potential (i.e. E K+ = -90mV, E Na+= +60mV) • Potassium is more strongly affecting the resting membrane potential because it has higher membrane permeability at rest and because there is more K+ inside of the cell Movement of ions across membrane depends on: • Electrochemical gradient • Electrochemical gradient: combination of electrical gradients and concentration gradients • Each ion has its own electrochemical gradient. • K+ has a weak outward gradient. • Na+ has a strong inward gradient because there is a strong inward concentration gradient and strong electrical gradient. • At rest, there is high K+ permeability but a weak driving force • At rest, there is low Na+ permeability because of the few channels even though it has a strong driving force • Permeability of membrane • If you change the permeability, you change the ion flow across the membrane • If you change ion flow, you change the membrane potential • Depolarization is when the Vm becomes more positive (an increase in Na+ permeability would cause this) • Hyperpolarization is when the Vm becomes more negative (an increase in K+ permeability would cause this) • Repolarization is when the Vm becomes more neutral (at rest) Common Hormone Pathways
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